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Abstract:

An improved active grate consisting of at least two elongated rockers
positioned parallel to one and another, each rocker having a lower
surface and an upper surface and configured to rotate back and forth
about their longitudinal axis. Each individual rocker is further
configured to rotate in the opposite direction of the adjacent rockers
such that any pair of adjacent rockers alternately forms a void allowing
material to pass through active grate when rotating in one direction into
a first position, and closes the void when rotated in the opposite
direction in a second position. The active grate finds particular utility
in a combined gasification/vitrification waste treatment system, where it
is used to pass partially oxidized materials from a gasification chamber
to a vitrification chamber. The rockers include a coolant loop through
the longitudinal axis of the rockers.

Claims:

1. An active grate comprising at least two elongated rockers positioned
parallel to one another, each rocker having a lower surface and an upper
surface, each of said rockers further configured to rotate about their
longitudinal axes to form a void allowing material to pass through said
active grate when at least one of said rockers is in a first position and
to close said void when two adjacent rockers are in a second position.

2. The improved active grate of claim 1, wherein at least one pair of
rockers is operable to displace the material away from said active grate
in said first position.

3. The active grate of claim 1, wherein at least one pair of rockers is
operable to provide a crushing force on the material when rotated between
said first and second positions.

4. The active grate of claim 1 further comprising a coolant loop
configured to flow coolant through at least one of the rockers.

16. The active grate of claim 1, wherein the upper surface of each rocker
is planar.

17. A method for allowing material to pass from a first chamber of a high
temperature system to a second chamber of the high temperature system,
the method comprising: rotating an elongated rocker about a longitudinal
axis of said rocker, said rocker having a lower surface and an upper
surface; forming a void between said rocker and an adjacent rocker
positioned parallel to said rocker, when said rocker is rotated about the
longitudinal axis of said rocker to a first position; and closing the
void when said rocker is rotated about the longitudinal axis to a second
position.

18. The method of claim 17, wherein said rocker and said adjacent rocker
are provided between the first chamber and the second chamber, the method
further comprising passing the material through said void.

19. The method of claim 17, further comprising displacing at least a
portion of the material in an upward direction when said rocker is
rotated to the first position.

20. The method of claim 17, further comprising crushing at least a
portion of the material between said rocker and said adjacent rocker when
said rocker is rotated from the first position to the second position.

21. The method of claim 17, further comprising cooling said rocker by
flowing a coolant through said rocker.

22. The method of claim 21, wherein said coolant is one or more of water,
ethylene glycol, paraffinic based heat transfer fluids, silicone based
heat transfer fluids, hydrocarbon heat transfer fluids, and combinations
thereof.

23. The method of claim 21, wherein said coolant is steam.

24. The method of claim 21, wherein said coolant is a mist of liquid
droplets.

25. A system comprising: a gasification unit for at least partially
converting organic components of a feed stream to a hydrogen rich gas and
ash; a joule heated vitrification unit downstream from the gasification
unit and configured to convert inorganic materials and ash into glass,
the vitrification unit having a plasma for converting carbon and products
of incomplete gasification into hydrogen rich gas; and an active grate
disposed between said gasification unit and the vitrification unit, the
grate comprising a rocker positioned parallel to an adjacent rocker, each
rocker having a lower surface and an upper surface, wherein said rocker
is configured to rotate about a longitudinal axis of said rocker to a
first position to form a void to allow material to pass from the
gasification unit to the vitrification unit through said active grate,
said rocker further configured to rotate to a second position to close
said void.

26. The system of claim 25, wherein said adjacent rocker is configured to
rotate in a direction opposite said rocker.

27. The system of claim 25, wherein said rocker further comprises a
coolant loop for flowing a coolant therethrough.

Description:

TECHNICAL FIELD

[0001] The present invention relates generally to a methods and apparatus
for processing feedstocks containing organic materials. More
specifically, the present invention relates to a grate particularly
suited to use in partial oxidation gasification systems. The present
invention finds particularly utility when used in an integrated partial
oxidation gasification and vitrification system used for recovering the
energy value from the organic portions of heterogeneous feedstocks while
converting the inorganic portions to a safe and useable form.

BACKGROUND OF THE INVENTION

[0002] U.S. patent application Ser. No: 11/432,826, filed May 12, 2006 and
entitled "COMBINED GASIFICATION AND VITRIFICATION SYSTEM" (hereafter the
"combined system" and incorporated in its entirety herein by this
reference) disclosed an improved method for processing organic and
heterogeneous feedstocks. The description of the combined system
describes a system that is capable of treating mixtures of inorganic
materials, biomass, and fossil-based organic materials and their
derivatives, including waste derived from the production and use of such
fossil-based organic materials, and converting them into a clean fuel gas
and an environmentally stable glass. The combined system consists
generally of a gasification unit which converts all or a portion of the
organic components of waste to a hydrogen rich gas and ash in
communication with a joule heated vitrification unit which converts
inorganic materials and ash formed in the gasification unit into glass,
and may further include a plasma which converts carbon and products of
incomplete gasification formed in the gasification unit into a hydrogen
rich gas.

[0003] As described in the combined system, organic or heterogeneous
mixtures of organic and inorganic feed stocks are first fed into the
gasification unit where all or part of the organic portion of the feed
stock are gasified. To assist in gasification, the materials are mixed
with oxygen in the gasification unit using oxygen, air, carbon dioxide,
oxygen enriched air, steam, and combinations thereof.

[0004] Within the partial oxidation gasification system, all or part of
the organic portion of the feed stock is gasified. The effluent from the
gasification process includes a gaseous portion, principally made up of
carbon monoxide, hydrogen, and light hydrocarbon gasses, together with a
solid and liquid portion, which includes unreacted and partially reacted
organic materials such as carbon char, together with the inorganic
portion of the feed stock, which may also include ash from the
gasification process.

[0005] The effluent is then fed directly from the gasification system into
a joule heated plasma reaction chamber to pyrolize and gasify the
remaining solid and liquid organic materials, and to allow sufficient
residence time and mixing to form the ash and other remaining inorganic
portions of the feed stock into stable, vitrified glass.

[0006] The combined system further includes a feedback control device
which measured effluent gasses, the flow rates of the feedstock, and the
flow rates of the oxidant. Using that information, the feedback control
device determines whether complete combustion was occurring in the
gasification unit. Having recognized an undesirable operation, the
feedback control device could then change the feed rates for one or both
of the oxidant or the feedstock, thereby preventing complete combustion
in the gasification unit.

[0007] For example, if the gasification unit is configured as a downdraft
gassifier, the feedback control device could control a means for
transporting organic material down the axial length of the downdraft
gasifier. In this manner, the flow rate of the feedstock through the
gassifier could be increased or decreased. The combined system disclosed
several means for transporting organic material down the axial length of
a downdraft gasifier and into the vitrification system including, but not
be limited to, an auger, a rake, an agitating grate, one or more rotating
drums, a piston, and combinations thereof.

[0008] While the agitating grate described in the combined system
generally accomplishes the purposes of the combined system, the present
invention overcomes drawbacks discovered when using an agitating grate as
described in the combined system. Nevertheless, the present invention
should not be limited to use in the combined system. Rather, the present
invention is broadly applicable in any high temperature system where
there is a desire to transfer solid materials at a controlled rate from
one chamber to another. Accepting that caveat, and not meant to be
limiting, it is useful for illustrative purposes to describe the
advantages of the present invention in terms of some of the drawbacks of
the agitating grate used in the combined system to enhance an
understanding and appreciation of the present invention.

[0009] One difficulty that the combined system was designed to overcome
was the failure of prior art systems to effectively and efficiently
process heterogeneous feed stocks. One aspect of these heterogeneous feed
stocks related to the agitating grate interposed between the gasifier and
the joule heated melter of the combined system is the tendency of certain
materials to block or plug different parts of the grate. When that
happens, the gas flow circumvents the blocked or plugged section of the
grate, and flows to the unblocked or unplugged sections. This, in turn,
causes more rapid oxidation of the materials in the unplugged sections,
and slower oxidation of the plugged sections, further exacerbating the
problem as the more oxidized portions are reduced in size and thus
generally flow through the grate while the less oxidized portions are not
reduced, and tend to add to the clogged area of the grate.

[0010] Accordingly, there is a need for an improved means by which
materials processed in one chamber of a high temperature system may be
transferred to a second chamber of the high temperature system.

SUMMARY OF THE INVENTION

[0011] It is therefore an object of the present invention to provide an
improved method and apparatus by which materials processed in one chamber
of a high temperature system may be transferred to a second chamber of
the high temperature system. It is a further object of the present
invention to provide an improved method and apparatus by which materials
processed in one chamber of a high temperature system may be crushed and
reduced in size, thereby facilitating the transfer of those materials to
a second chamber of the high temperature system. It is a further object
of the present invention to provide an active grate wherein materials
processed in one chamber of a high temperature system may agitated,
thereby facilitating the flow of those materials to a second chamber of
the high temperature system at a controlled rate. It is a further object
of the present invention to provide an active grate in a waste treatment
system interposed between a gasification unit capable of converting all
or a portion of the organic components of a feed stream to a hydrogen
rich gas and ash and a joule heated vitrification unit capable of
converting inorganic materials and ash formed in the gasification unit
into glass, and which, while not meant to be limiting, may further
include a plasma capable of converting carbon and products of incomplete
gasification formed in the gasification unit into a hydrogen rich gas.

[0012] These and other objects of the present invention are an improved
active grate consisting of at least two elongated rockers positioned
parallel to one and another, each rocker having a lower surface and an
upper surface. Preferably, but not meant to be limiting, the improved
grate of the present invention consists of several rockers. Each of said
rockers are configured to rotate back and forth about their longitudinal
axis. As used herein, the term longitudinal means along the major (or
long) axis of the rocker.

[0013] Each individual rocker is further configured to rotate in the
opposite direction of the adjacent rockers. Preferably, but not meant to
be limiting, the lower surface is curved and the upper surface is angled.
In this manner, any pair of adjacent rockers alternately forms a void
allowing material to pass through active grate when rotating in one
direction into a first position, and closes the void when rotated in the
opposite direction to a second position.

[0014] While it is preferred that the lower surface is curved and the
upper surface is angled, and such an arrangement is shown for
illustrative purposes in the preferred embodiment described herein to
promote an understanding and appreciation of the present invention, those
having ordinary skill in the art having the benefit of this disclosure
will recognize that the same effect can be accomplished with alternative
geometries of the rocker surfaces. For example, and not meant to be
limiting, an acceptable alternative for the curved lower surface might
have several adjacent flat surfaces that approximated a curve. Similarly,
the top surface could simply be planer. Accordingly, all such alternative
geometries for both the upper and lower surfaces, including without
limitation all combinations of all such alternative geometries, are
included in this disclosure, and should be considered as contemplated by
and part of the present invention.

[0015] The active grate of the present invention provides an advantage
over prior art grates because as they are rotated, any pair of rockers
alternately displaces material away from the active grate and then forms
a void in the area between the rockers. In this manner, any material on
top of the active grate is agitated up and allowed to fall down toward a
void, thereby dispersing any large pieces across the upper surface of the
active grate, and thus facilitating the regular and even flow of material
through the active grate. Further, when the rockers are rotated from the
first position to the second position, closing the void between them, any
material in between these rockers is crushed between the adjacent edges
of the rockers, thereby crushing and reducing the size of any large
pieces, thus allowing their passage through the voids. This also
facilitates the regular and even flow of material through the active
grate.

[0016] Preferably, but not meant to be limiting, the active grate of the
present invention is used in a combined gasification/vitrification waste
treatment system. These systems consist of a gasification unit capable of
converting all or a portion of the organic components of a feed stream to
a hydrogen rich gas and ash and a joule heated vitrification unit capable
of converting inorganic materials and ash formed in the gasification unit
into glass. Preferably, but not meant to be limiting, the vitrification
unit may further have a plasma capable of converting carbon and products
of incomplete gasification formed in the gasification unit into a
hydrogen rich gas. When used in a combined gasification/vitrification
waste treatment system, the active grate of the present invention can
effectively control and regulate an even rate of flow of materials from
the gasification unit to the vitrification unit.

[0017] In these and other waste treatment systems wherein the active grate
of the present invention can be advantageously deployed, the temperatures
can be very high. These high temperatures can put a significant stain on
the rockers of the active grate. Accordingly, it is preferred that the
rockers include a coolant loop through the longitudinal axis of the
rockers. By flowing a coolant through the coolant loop of the rockers,
they can be maintained at a temperature that reduces the wear and tear on
the rockers. Preferable coolants include, but are not limited to water,
steam, ethylene glycol, paraffinic based heat transfer fluids, silicone
based heat transfer fluids, and hydrocarbon heat transfer fluids. Water
or other of these coolant fluids may be provided as a liquid, mist in a
carrier gas, or steam. In this manner, the cooling effects of the water
can be realized without generating excessive pressure changes in the
rockers.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following detailed description of the embodiments of the
invention will be more readily understood when taken in conjunction with
the following drawings, wherein:

[0019] FIG. 1 is an overhead view of a preferred embodiment of the
apparatus of the present invention.

[0020] FIG. 2 is a side view of a preferred embodiment of the apparatus of
the present invention.

[0021] FIG. 3a is a cut away schematic view of a preferred embodiment of
the apparatus of the present invention showing the position of the
rockers in a first position, FIG. 3b is a cut away schematic view of a
preferred embodiment of the apparatus of the present invention showing
the position of the rockers in a in a second position, and FIG. 3c is a
cut away schematic view of a preferred embodiment of the apparatus of the
present invention showing the position of the rockers in a in an
intermediate position.

[0022] FIG. 4 is a schematic view of a preferred embodiment of the
apparatus of the present invention used in conjunction with a combined
system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] For the purposes of promoting an understanding of the principles of
the invention, reference will now be made to the embodiments illustrated
in the drawings. Specific language will be used to describe the same, and
like reference numbers will refer to like components of the invention. It
will nevertheless be understood that no limitations of the inventive
scope is thereby intended, as the scope of this invention should be
evaluated with reference to the claims appended hereto. Alterations and
further modifications in the illustrated devices, and such further
applications of the principles of the invention as illustrated herein are
contemplated as would normally occur to one skilled in the art to which
the invention relates.

[0024] For the purposes of promoting an understanding of the principles of
the invention, FIG. 1 is an overhead view of a preferred embodiment of
the active grate of the present invention and FIG. 2 is a side view of
the same preferred embodiment of the active grate of the present
invention. As shown in FIG. 1, a series of rockers 1 each having a center
dowel 2 are arranged in a parallel fashion inside of a frame 3 such that
center dowel 2 extends through frame 3 at each end. At one end of frame
3, alternating ends of every other center dowel 2 are attached to rocker
arm 4 and rocker arms 4 are further attached to a shaker 5. In this
arrangement, as shown in FIG. 2, by moving the shaker 5, alternating
rocker arms 4 may be made to rotate about the center dowels 2 in unison
with one and another.

[0025] A coolant loop 6 is connected through the longitudinal axis of the
rockers 1 allowing a coolant to be flowed through the rockers 1 and
thereby maintain the rockers at a suitable temperature for operation. A
heat sink and pump 7 are further integral to coolant loop 6, and are used
to facilitate the circulation of coolant through the rockers, and the
removal of heat from the coolant and thus the coolant loop 6 and the
rockers 1. The heat sink can be of any type known to those having skill
in the art, including without limitation, a radiator or a heat exchanger.

[0026] At the other end of the frame 3, alternating ends of the remaining
center dowels 2 are attached to rocker arms 4 and rocker arms 4 are
further attached to shaker 5. In this arrangement, by moving shakers 5 in
a coordinated fashion, adjacent alternating rocker arms 4 may be made to
rotate about the center dowels 2 in a direction opposite to the adjacent
rockers 1.

[0027] FIG. 3 is a cut away schematic view of a preferred embodiment of
the apparatus of the present invention showing how the adjacent pairs of
rockers interact as they are rotated about a central axis, and, while not
meant to be limiting, a preferred shape of the rockers 1 across their
longitudinal axis. FIG. 3a shows the position of the rockers 1 in a first
position. As shown in FIG. 3a, in between alternating pairs of adjacent
rocker arms 1 a void is formed in a first position allowing material to
pass through the active grate. When the shakers 5 (as shown in FIGS. 1
and 2) are moved at each end of the active grate in opposite directions,
each of the rockers 1 are caused to rotate in a direction opposite to any
adjacent rockers 1. As shown in FIG. 3b, the voids close in a second
position, and as shown in FIG. 3c, another void is formed in a third
position.

[0028] Comparing FIGS. 3a and 3c, it should be noted that the adjacent
pairs of rockers 1 will alternatively form a void and then act to
displace material placed on the rockers 1 in an upward direction. It
should further be noted that as rockers 1 are rotated from a first
position to a second position, any material caught in the void in between
rockers 1 will be crushed by the rotation of the rockers. In this manner,
materials on top of the grate that might otherwise tend to block the
grate, or to block portions of the grate, are made to pass through the
grate by agitating those materials, and by crushing and reducing the size
of those materials.

[0029] FIG. 4 is a schematic view of a preferred embodiment of the
apparatus of the present invention used in conjunction with a combined
system. As shown in FIG. 4, a waste treatment system consisting of a
gasification unit 8 capable of converting all or a portion of the organic
components of a feed stream to a hydrogen rich gas and ash is attached to
the frame 3 of the improved active grate of the present invention. A feed
stream of materials are fed into the gasification unit 8 where all or a
portion of the organic components are converted to a hydrogen rich gas
and ash. This ash and any other solids are then passed through the
improved active grate of the present invention to a joule heated
vitrification unit 9. This joule heated vitrification unit 9 is capable
of converting inorganic materials and ash formed in the gasification unit
into glass, and further contains a plasma 10 capable of converting carbon
and products of incomplete gasification formed in the gasification unit
into a hydrogen rich gas.

[0030] While this particular configuration is preferred, the present
invention should in no way be limited to this configuration, and it
should be understood that this configuration was selected merely for
illustrative purposes.

[0031] While the invention has been illustrated and descried in detail in
the drawings and foregoing description, the same is to be considered as
illustrative and not restrictive in character. Only certain embodiments
have been shown and described, and all changes, equivalents, and
modifications that come within the spirit of the invention described
herein are desired to be protected. Any experiments, experimental
examples, or experimental results provided herein are intended to be
illustrative of the present invention and should not be considered
limiting or restrictive with regard to the invention scope. Further, any
theory, mechanism of operation, proof, or finding stated herein is meant
to further enhance understanding of the present invention and is not
intended to limit the present invention in any way to such theory,
mechanism of operation, proof, or finding.

[0032] Thus, the specifics of this description and the attached drawings
should not be interpreted to limit the scope of this invention to the
specifics thereof. Rather, the scope of this invention should be
evaluated with reference to the claims appended hereto. In reading the
claims it is intended that when words such as "a", "an", "at least one",
and "at least a portion" are used there is no intention to limit the
claims to only one item unless specifically stated to the contrary in the
claims. Further, when the language "at least a portion" and/or "a
portion" is used, the claims may include a portion and/or the entire
items unless specifically stated to the contrary. Finally, all
publications, patents, and patent applications cited in this
specification are herein incorporated by reference to the extent not
inconsistent with the present disclosure as if each were specifically and
individually indicated to be incorporated by reference and set forth in
its entirety herein.